The invention relates to a multiple-sheet monitoring device and, more particularly, to such a device for sheet-processing machines, having a rotatable roller disposed underneath a sheet to be conveyed, a sensing element pivotally disposed at a spaced distance above the roller, and a switching element fixed in position, the switching element being actable upon in accordance with the pivoting position of the sensing element.
A multiple-sheet monitoring device of this general type has become known heretofore from the published German Patent Document DE 38 23 202 C2.
The lever for operating the switch and for supporting or holding the sensing element is disposed on a cyclically operated shaft in the aforementioned German Patent Document DE 38 23 202 C2. A continual reciprocating movement of the lever produces oscillations of the entire device and therefore leads to inaccurate measurement results.
It is accordingly an object of the invention to provide a multiple-sheet monitoring device which operates with greater precision than the heretofore known device of this general type.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a multiple-sheet monitoring device for a sheet-processing machine, having a plurality of sensing elements pivotally disposed above a sheet and an overlapping sheet stream, respectively, at a spaced distance therefrom, and a switching element disposed in a fixed position and being actable upon in accordance with the pivoting position of the sensing elements, the sensing elements being arranged over the format width of the sheets and the overlapping sheet stream, respectively, to be conveyed, comprising an adjustment device for adjusting all of the sensing elements in common to the thickness of a sheet to be processed.
In accordance with another aspect of the invention, there is provided a multiple-sheet monitoring device for sheet-processing machines, having a rotatable roller disposed underneath a sheet to be conveyed, a sensing element pivotally disposed at a spaced distance above the roller, and a switching element fixed in position, the switching element being actable upon in accordance with the pivoting position of the sensing element, comprising a pivotable cross member, and an actuating element for the switching element mounted on the cross member so as to be fixed against rotation relative thereto.
In accordance with another feature of the invention, the multiple-sheet monitoring device includes at least one additional sensing element, and all of the sensing elements cooperate with only one switching element.
In accordance with a further aspect of the invention, there is provided an assembly including the multiple-sheet monitoring device, wherein the multiple-sheet monitoring device is disposed in vicinity of the beginning of a feed table.
In accordance with an added feature of the invention, the sensing element is a roller.
In accordance with an additional feature of the invention, the multiple-sheet monitoring device includes a counter-roller spaced from the sensing roller, and an adjusting screw for indirectly adjusting the spaced distance between the sensing roller and the counter-roller via a pivotable support.
In accordance with yet another feature of the invention, the switching element is mounted on a holder and is adjustable in common therewith by the adjusting screw.
In accordance with yet a further feature of the invention, the spaced distance between the sensing roller and the counter-roller is slightly greater than the thickness of the sheet and an overlapping sheet stream, respectively, to be monitored.
In accordance with yet an added feature of the invention, a rotatable roller is mounted underneath the sheet and an overlapping sheet stream, respectively, to be conveyed.
In accordance with yet an additional feature of the invention, the roller is disposed opposite to the sensing element.
In accordance with still another feature of the invention, all of the sensing elements cooperate with only one switch element.
In accordance with still a further feature of the invention, the sensing elements are rollers.
In accordance with still an added feature of the invention, the multiple-sheet monitoring device includes a respective counter-roller spaced from each of the sensing rollers, and an adjusting screw for indirectly adjusting the spaced distance between the respective sensing rollers and counter-rollers via a pivotable support.
In accordance with still an additional feature of the invention, the spaced distance between the respective sensing rollers and counter-rollers is slightly greater than the thickness of the sheet and an overlapping sheet stream, respectively, to be monitored.
In accordance with another feature of the invention, a plurality of rotatable rollers are mounted underneath the sheet and the overlapping sheet stream, respectively, to be conveyed.
In accordance with a concomitant aspect of the invention, there is provided an assembly including the multiple-sheet monitoring device, wherein the rotatable rollers, respectively, are disposed opposite the plurality of sensing elements, respectively.
Thus, a significant advantage of the invention lies in the arrangement of a number of sensing elements, at least two thereof, side-by-side on the cross member. Due to this feature, the sheet and the overlapping sheet stream, respectively, can be monitored simultaneously at a number of locations. In particular, in an edge region of the sheet and the overlapping sheet stream, respectively, dog-eared corners are reliably detectable.
A further advantage of the invention is the arrangement of an actuating element for a switching element that is provided, so that it is fixed against rotation relative to the pivotable cross member of the sensing elements.
It is therefore necessary for only one switch to be provided, because each sensing element is arranged so that it is fixed against rotation relative to the pivotable cross member, and each deflection of a sensing element results in the actuation of the switch.
The multiple-sheet monitoring device is preferably installed at the beginning of the conveyor table. Due to this feature, a large time window is afforded for stopping the sheet-processing machine, in particular a printing machine, even at high processing speeds.
The sheet and overlapping sheet stream, respectively, are advantageously monitored without contact with the sensing roller, because only when multiple sheets or faulty sheets are present is the sensing roller contacted and a pivoting movement initiated, which causes a stoppage of the sheet conveying system.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a multiple-sheet monitoring device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: